Closing the evidence gap: Capillary high-sensitivity troponin I verification in an African population using point of...

High sensitivity cardiac troponin I (hs-cTnI) assays are central to the early diagnosis and rule-out of acute myocardial infarction (AMI). In resource-limited settings, point-of-care (POC) platforms using capillary blood may reduce turnaround time and improve access to timely decision-making. This study evaluated the performance of capillary hs-cTnI POC sampling in an African population.

This cross-sectional method comparison study evaluated paired capillary hs-cTnI measurements obtained on POC against corresponding venous serum and plasma samples analysed on a central laboratory assay. Samples were collected from adults presenting with suspected AMI to Charlotte Maxeke Johannesburg Academic Hospital Emergency Department. Analytical verification was performed in accordance with Clinical and Laboratory Standards Institute protocols. Agreement was assessed using Bland Altman analysis. Diagnostic concordance at sex-specific 99th percentile decision thresholds and misclassification rates were determined.

In this study, 110 patients were recruited, of whom 91 were deemed eligible for analysis. Capillary hs-cTnI showed moderate correlation with both plasma (r_s = 0.788; 95% CI 0.694-0.855) and serum (r_s = 0.791; 95% CI 0.699-0.857). Mean bias of capillary versus plasma was -15.9% (-173% to +143%) and - 12.9% (-171% to +145%) compared with serum. Serum comparison met the predefined allowable minimum bias of 13.6%. Overall agreement at the 99th percentile was 92.1% (83/91), with substantial inter-method agreement (κ >0.75). No significant asymmetry in discordant classifications was observed (p = 0.7266; 95% CI -8.27 to 3.88).

Capillary whole-blood hs-cTnI testing demonstrated acceptable analytical agreement and high clinical concordance with central laboratory measurement, supporting its implementation to enhance rapid AMI assessment in resource-limited emergency settings.